One-Way Cable Modem and Firewall/Router?

[Jud]

After years of dialup-only service, I have moved to a new location and
gotten broadband access.  Only 'one-way' broadband access is available,
through an SB3100 Motorola/General Instrument cable modem that
communicates upstream via dialup, downstream via cable.

I was thinking I ought to set up a hardware firewall, and am considering
the Netgear WGT624 router (Atheros chipset) for this purpose.  I would
only be hooking up a single desktop computer, and wouldn't be needing
wireless connection just yet (though the router's capability in this
regard will be nice for future home networking).

Does anyone know of any problems (or tips) specifically concerning use
of a router/firewall with a one-way cable modem?

Jud